Control apparatus for hybrid vehicle

ABSTRACT

A control apparatus for a hybrid vehicle includes an internal combustion engine and a generator motor, a capacitor, and a driving force assisting unit. Further, the control device includes a switching unit that selects an appropriate traveling range from a plurality of traveling ranges including at least a normal traveling range and a charging priority range for preferentially charging the capacitor and switches the range, and a threshold value increasing unit that increases, when the charging priority range is selected by the switching unit, the predetermined determination threshold value as compared to when the normal traveling range is selected by the switching unit.

TECHNICAL FIELD

The present invention relates to a control apparatus for a hybridvehicle.

Priority is claimed on Japanese Patent Application No. 2007-183462, thecontent of which is incorporated herein by reference.

BACKGROUND ART

In the past, there has been known a hybrid vehicle that includes, forexample, an internal combustion engine and a motor as driving sourcesand transmits a driving force from at least one of the internalcombustion engine and the motor to driving wheels, thereby traveling.While traveling on an ascending road, the hybrid vehicle relativelyreduces regenerative torque of the electric motor. Thereby, the hybridvehicle prevents excessive deceleration feeling from occurring, andensures desired drivability (for example, refer to Patent Document 1).

For example, when the hybrid vehicle moves from a flat road to anascending road, if the operation amount of the accelerator operated by adriver becomes larger than a predetermined threshold value, the poweringoperation of the electric motor is performed, so that the driving forceof the internal combustion engine is assisted by the driving force ofthe electric motor.

-   [Patent Document 1] Japanese Unexamined Patent Application, First    Publication No. 2005-269793

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

Meanwhile, when a vehicle travels on the ascending road, merely, thecontrol apparatus for a hybrid vehicle according to the related artrelatively decreases the regenerative torque of the electric motor orincreases the assist amount of the electric motor for assisting theinternal combustion engine. Accordingly, for example, if the vehicletravels on the ascending road for a long time, or if the ascendinggradient of the ascending road corresponds to a relatively highgradient, there is a concern that the electrical energy required fordriving the electric motor is insufficiently stored in the capacitor.For this reason, there is a problem in that it is not possible to ensuredesired ascending performance.

The present invention has been made in consideration of the abovecircumstances, and has an object of providing a control apparatus for ahybrid vehicle that can ensure desired ascending performance.

Means for Solving the Problems

In order to achieve the object, the present invention employs thefollowings.

That is,

(1) A control apparatus for a hybrid vehicle according to an embodimentof the invention includes an internal combustion engine and a generatormotor that are used as power sources of a vehicle, a capacitor thatsupplies and receives electrical energy to and from the generator motor,and a driving force assisting unit that assists a driving force of theinternal combustion engine by a driving force of the generator motorwhen a driving force command of the vehicle is larger than apredetermined determination threshold value. The control device includesa switching unit that selects an appropriate traveling range from aplurality of traveling ranges including at least a normal travelingrange and a charging priority range for preferentially charging thecapacitor and switches the range, and a threshold value increasing unitthat increases, when the charging priority range is selected by theswitching unit, the predetermined determination threshold value ascompared to when the normal traveling range is selected by the switchingunit.

(2) The control apparatus for a hybrid vehicle according to the above(1) may further include a generated power increasing unit thatincreases, when the charging priority range is selected by the switchingunit, the amount of power generated by the generator motor as comparedto when the normal traveling range is selected by the switching unit.

(3) A control apparatus for a hybrid vehicle according to anotherembodiment of the invention includes an internal combustion engine and agenerator motor that are used as power sources of a vehicle, a capacitorthat supplies and receives electrical energy to and from the generatormotor, and a driving force assisting unit that assists a driving forceof the internal combustion engine by a driving force of the generatormotor when a driving force command of the vehicle is larger than apredetermined determination threshold value. The control device includesa gradient acquisition unit that acquires an ascending gradient of atraveling road for the vehicle, and a threshold value increasing unitthat increases the predetermined determination threshold value when theascending gradient acquired by the gradient acquisition unit is largerthan the predetermined gradient.

(4) The control apparatus for a hybrid vehicle according to the above(3) may further include a generated power changing unit. The generatedpower changing unit sets the amount of power generated by the generatormotor so that the amount of generated power is increased with theincrease of the ascending gradient, when the ascending gradient acquiredby the gradient acquisition unit is a predetermined threshold gradientor less; and sets the amount of generated power so that the amount ofgenerated power is decreased with the increase of the ascendinggradient, when the ascending gradient is larger than a predeterminedthreshold gradient.

(5) The control apparatus for a hybrid vehicle according to the above(1) may further include a generated power increasing unit that increasesthe amount of power generated by the generator motor when the travelingstate of the vehicle is a constant speed traveling state and thecharging priority range is selected by the switching unit.

(6) The control apparatus for a hybrid vehicle according to the above(3) may further include a generated power changing unit. The generatedpower changing unit sets the amount of power generated by the generatormotor so that the amount of generated power is increased with theincrease of the ascending gradient, when the traveling state of thevehicle is a constant speed traveling state and the ascending gradientacquired by the gradient acquisition unit is a predetermined thresholdgradient or less; and sets the amount of generated power so that theamount of generated power is decreased with the increase of theascending gradient, when the traveling state of the vehicle is aconstant speed traveling state and the ascending gradient is larger thana predetermined threshold gradient.

(7) The control apparatus for a hybrid vehicle according to the above(1) may further include a generated power increasing unit. The generatedpower increasing unit prohibits the stop of an idle operation of theinternal combustion engine during the stop of the vehicle when thecharging priority range is selected by the switching unit, and increasesthe amount of power generated by the generator motor during the stop ofthe vehicle as compared to when the normal traveling range is selectedby the switching unit.

(8) The control apparatus for a hybrid vehicle according to the above(3) may further include a generated power increasing unit. The generatedpower increasing unit prohibits the stop of an idle operation of theinternal combustion engine during the stop of the vehicle when theascending gradient acquired by the gradient acquisition unit is largerthan a predetermined gradient, and increases the amount of powergenerated by the generator motor while the idle operation of theinternal combustion engine is performed during the stop of the vehicleas compared to when the ascending gradient is a predetermined gradientor less.

(9) A control apparatus for a hybrid vehicle according to anotherembodiment of the invention includes an internal combustion engine and agenerator motor that are used as power sources of a vehicle, a capacitorthat supplies and receives electrical energy to and from the generatormotor, and a driving force assisting unit that assists a driving forceof the internal combustion engine by a driving force of the generatormotor when a driving force command of the vehicle is larger than apredetermined determination threshold value. The control device includesa switching unit that selects an appropriate traveling range from aplurality of traveling ranges including at least a normal travelingrange and a charging priority range for preferentially charging thecapacitor and switches the range, and a generated power increasing unitthat increases the amount of power generated by the generator motorwhile the idle operation of the internal combustion engine is performedduring the stop of the vehicle when the charging priority range isselected by the switching unit as compared to when the normal travelingrange is selected by the switching unit.

(10) The control apparatus for a hybrid vehicle according to the above(9) may further include a residual capacity acquisition unit thatacquires the residual capacity of the capacitor, and an idle speedsetting unit. The idle speed setting unit sets an idle speed, while theidle operation of the internal combustion engine is performed during thestop of the vehicle, according to the residual capacity acquired by theresidual capacity acquisition unit, when the charging priority range isselected by the switching unit. When the residual capacity is apredetermined residual capacity or less, the idle speed setting unit mayincrease the idle speed as compared to when the residual capacity islarger than a predetermined residual capacity.

(11) The control apparatus for a hybrid vehicle according to the above(9) may further include a residual capacity acquisition unit thatacquires the residual capacity of the capacitor, and an idle speedsetting unit. The idle speed setting unit sets an idle speed, while theidle operation of the internal combustion engine is performed during thestop of the vehicle, according to the residual capacity acquired by theresidual capacity acquisition unit, when the charging priority range isselected by the switching unit. The idle speed setting unit may set theidle speed so that the idle speed is increased with the decrease of theresidual capacity.

(12) The control apparatus for a hybrid vehicle according to the above(9) may further include a residual capacity acquisition unit, adetermination unit, and a threshold residual capacity increasing unit.The residual capacity acquisition unit acquires the residual capacity ofthe capacitor. The determination unit determines whether a powergenerating operation is performed by the generator motor during the idleoperation, according to the determination result of whether the residualcapacity acquired by the residual capacity acquisition unit, while theidle operation of the internal combustion engine is performed during theduring the stop of the vehicle, is a predetermined threshold residualcapacity or less. The threshold residual capacity increasing unitincreases the predetermined threshold residual capacity when thecharging priority range is selected by the switching unit as compared towhen the normal traveling range is selected by the switching unit.

(13) The control apparatus for a hybrid vehicle according to the above(9) may further include an idle stop prohibiting unit. The idle stopprohibiting unit prohibits the stop of the idle operation of theinternal combustion engine during the stop of the vehicle when thecharging priority range is selected by the switching unit.

(14) A control apparatus for a hybrid vehicle according to anotherembodiment of the invention includes an internal combustion engine and agenerator motor that are used as power sources of a vehicle, a capacitorthat supplies and receives electrical energy to and from the generatormotor, and a driving force assisting unit that assists a driving forceof the internal combustion engine by a driving force of the generatormotor when a driving force command of the vehicle is larger than apredetermined determination threshold value. The control device includesa gradient acquisition unit, a traveling road determining unit, and agenerated power increasing unit. The gradient acquisition unit acquiresan ascending gradient of a traveling road for the vehicle. The travelingroad determining unit determines whether the traveling road is anascending road or a flat road, according to the ascending gradientacquired by the gradient acquisition unit. The generated powerincreasing unit increases the amount of power generated by the generatormotor while the idle operation of the internal combustion engine isperformed during the stop of the vehicle when the vehicle is stopped onthe ascending road as compared to when the vehicle is stopped on theflat road.

(15) A control apparatus for a hybrid vehicle according to anotherembodiment of the invention includes an internal combustion engine and agenerator motor that are used as power sources of a vehicle, a capacitorthat supplies and receives electrical energy to and from the generatormotor, and a driving force assisting unit that assists a driving forceof the internal combustion engine by a driving force of the generatormotor when a driving force command of the vehicle is larger than apredetermined determination threshold value. The control device includesa gradient acquisition unit, a traveling road determining unit, and agenerated power increasing unit. The gradient acquisition unit acquiresan ascending gradient of a traveling road for the vehicle. The travelingroad determining unit determines whether the traveling road is anascending road or a flat road, according to the ascending gradientacquired by the gradient acquisition unit. The generated powerincreasing unit increases idle speed and increases the amount of powergenerated by the generator motor while the idle operation of theinternal combustion engine is performed during the stop of the vehiclewhen the vehicle is stopped on the ascending road as compared to whenthe vehicle is stopped on the flat road.

(16) The control apparatus for a hybrid vehicle according to the above(1) may further include a gradient acquisition unit, a traveling roaddetermining unit, and a generated power increasing unit. The gradientacquisition unit acquires an ascending gradient of a traveling road forthe vehicle. The traveling road determining unit determines whether thetraveling road is an ascending road or a flat road, according to theascending gradient acquired by the gradient acquisition unit. Thegenerated power increasing unit increases the amount of power generatedby the generator motor while the idle operation of the internalcombustion engine is performed during the stop of the vehicle when thevehicle is stopped on the ascending road as compared to when the vehicleis stopped on the flat road.

(17) The control apparatus for a hybrid vehicle according to the above(1) may further include a gradient acquisition unit, a traveling roaddetermining unit, and a generated power increasing unit. The gradientacquisition unit acquires an ascending gradient of a traveling road forthe vehicle. The traveling road determining unit determines whether thetraveling road is an ascending road or a flat road, according to theascending gradient acquired by the gradient acquisition unit. Thegenerated power increasing unit increases idle speed and increases theamount of power generated by the generator motor while the idleoperation of the internal combustion engine is performed during the stopof the vehicle when the vehicle is stopped on the ascending road ascompared to when the vehicle is stopped on the flat road.

Effects of the Invention

According to the control apparatus for a hybrid vehicle of the above(1), when the charging priority range is selected, a predetermineddetermination threshold value corresponding to the driving force commandof the vehicle, which is used to determine whether the driving force ofthe internal combustion engine is assisted by the driving force of thegenerator motor, is increased as compared to when the normal travelingrange is selected. Accordingly, it is possible to suppress the drive ofthe generator motor in the charging priority range, to suppress thepower consumption required for driving the generator motor, and toprevent the residual capacity of the capacitor from being excessivelydecreased. Further, for example, even if a vehicle travels on anascending road for a long time, or even if the ascending gradient of anascending road corresponds to a relatively high gradient, it is possibleto ensure a desired driving force of the generator motor.

Furthermore, if the structure of the above (2) is employed, the amountof power generated by the generator motor is increased when the chargingpriority range is selected as compared to when the normal travelingrange is selected. Therefore, it is possible to increase the residualcapacity of the capacitor, and to easily ensure a desired driving forceof the generator motor.

In addition, according to the control apparatus for a hybrid vehicle ofthe above (3), when the ascending gradient becomes larger than apredetermined gradient, a predetermined determination threshold valuecorresponding to the driving force command of the vehicle, which is usedto determine whether the driving force of the internal combustion engineis assisted by the driving force of the generator motor, is increased.Accordingly, it is possible to suppress the drive of the generator motoron the ascending road, to suppress the power consumption required fordriving the generator motor, and to prevent the residual capacity of thecapacitor from being excessively decreased. Further, for example, evenif a vehicle travels on the ascending road for a long time, or even ifthe ascending gradient of the ascending road corresponds to a relativelyhigh gradient, it is possible to ensure a desired driving force of thegenerator motor.

Furthermore, if the structure of (4) is employed, the amount ofgenerated power is set to be increased with the increase of theascending gradient when the ascending gradient is a predeterminedthreshold gradient or less, and the amount of generated power is set tobe decreased with the increase of the ascending gradient when theascending gradient is larger than a predetermined threshold gradient.Therefore, it is possible to ensure desired ascending performance whileincreasing the residual capacity of the capacitor.

In addition, if the structure of (5) is employed, the amount ofgenerated power is increased in the constant speed traveling state wherethe charging priority range is selected. Therefore, a driving force ofthe vehicle is ensured by the internal combustion engine and the driveof the generator motor is suppressed, so that it is possible to increasethe residual capacity of the capacitor while ensuring desired vehicletraveling performance.

Further, if the structure of (6) is employed, the amount of generatedpower is set to be increased with the increase of the ascending gradientwhen the ascending gradient is a predetermined threshold gradient orless in the constant speed traveling state, and the amount of generatedpower is set to be decreased with the increase of the ascending gradientwhen the ascending gradient is larger than a predetermined thresholdgradient. Therefore, it is possible to ensure desired ascendingperformance while increasing the residual capacity of the capacitor.

Furthermore, if the structure of (7) is employed, when the chargingpriority range is selected and the vehicle is stopped, the stop of anidle operation is prohibited and the amount of generated power isincreased. Therefore, it is possible to increase the residual capacityof the capacitor by the power generation that is performed using thedriving force of the internal combustion engine.

In addition, if the structure of (8) is employed, when the ascendinggradient becomes larger than a predetermined gradient during the stop ofthe vehicle, the stop of an idle operation is prohibited and the amountof generated power is increased. Therefore, it is possible to increasethe residual capacity of the capacitor by the power generation that isperformed using the driving force of the internal combustion engine.Further, it is possible to ensure a desired driving force of thegenerator motor that is required for assisting the driving force of theinternal combustion engine on the ascending road.

Furthermore, according to the control apparatus for a hybrid vehicle ofthe above (9), when the charging priority range is selected, the amountof generated power is increased while the idle operation is performedduring the stop of the vehicle as compared to when the normal travelingrange is selected. Therefore, it is possible to increase the residualcapacity of the capacitor by the power generation that is performedusing the driving force of the internal combustion engine.

In addition, if the structure of (10) is employed, when the residualcapacity of the capacitor is a predetermined residual capacity or lesswhile the charging priority range is selected and the vehicle isstopped, idle speed is increased. Therefore, it is possible to increasedesired residual capacity by the power generation that is performedusing the driving force of the internal combustion engine.

Further, if the structure of (11) is employed, when the chargingpriority range is selected and the vehicle is stopped, the idle speed ischanged to be increased with the decrease of the residual capacity ofthe capacitor. Therefore, it is possible to increase desired residualcapacity by the power generation that is performed using the drivingforce of the internal combustion engine.

Furthermore, if the structure of (12) is employed, when the chargingpriority range is selected, a predetermined threshold residual capacity(that is, an upper limit threshold value for allowing the powergenerating operation to be performed) corresponding to the residualcapacity, which is used to determine whether the power generatingoperation is performed by the generator motor while the idle operationof the internal combustion engine is performed during the stop of thevehicle, is increased as compared to when the normal traveling range isselected. Accordingly, it is possible to increase a region, which allowsthe power generating operation to be performed, of the residual capacityof the capacitor, and to easily increase the residual capacity.

In addition, if the structure of (13) is employed, when the chargingpriority range is selected and the vehicle is stopped, the stop of theidle operation is prohibited. Accordingly, it is possible to increasethe residual capacity of the capacitor by the power generation that isperformed using the driving force of the internal combustion engine.Therefore, it is possible to ensure desired driving force of thegenerator motor.

Further, according to the control apparatus for a hybrid vehicle of theabove (14), since the amount of generated power is increased on theascending road during the stop of the vehicle, it is possible toincrease the residual capacity of the capacitor by the power generationthat is performed using the driving force of the internal combustionengine. Accordingly, it is possible to ensure a desired driving force ofthe generator motor that is required for assisting the driving force ofthe internal combustion engine on the ascending road.

Furthermore, according to the control apparatus for a hybrid vehicle ofthe above (15), since the amount of generated power is increased and theidle speed is increased on the ascending road during the stop of thevehicle, it is possible to increase the residual capacity of thecapacitor by the power generation that is performed using the drivingforce of the internal combustion engine. Accordingly, it is possible toensure a desired driving force of the generator motor that is requiredfor assisting the driving force of the internal combustion engine on theascending road.

In addition, if the structure of (16) is employed, when the vehicletravels in the charging priority range, the drive of the generator motoris suppressed, the power consumption required for driving the generatormotor can be suppressed, and the amount of generated power is increasedon the ascending road during the stop of the vehicle. Accordingly, it ispossible to increase the residual capacity of the capacitor by the powergeneration that is performed using the driving force of the internalcombustion engine. Therefore, it is possible to ensure a desired drivingforce of the generator motor that is required for assisting the drivingforce of the internal combustion engine on the ascending road.

Further, if the structure of (17) is employed, when the vehicle travelsin the charging priority range, the drive of the generator motor issuppressed, the power consumption required for driving the generatormotor can be suppressed, and the idle speed is increased while theamount of generated power is increased on the ascending road during thestop of the vehicle. Accordingly, it is possible to increase theresidual capacity of the capacitor by the power generation that isperformed using the driving force of the internal combustion engine.Therefore, it is possible to ensure a desired driving force of thegenerator motor that is required for assisting the driving force of theinternal combustion engine on the ascending road.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing the structure of a hybrid vehicle according toan embodiment of the invention.

FIG. 2 is a graph showing an example of the change of an assistperforming determination threshold value in a predetermined normal stateand a predetermined charging priority state according to the embodiment.

FIG. 3 is a graph showing an example of a correspondence relationshipbetween an assist amount and an ascending gradient DE or an acceleratoropening AP in an acceleration state according to the embodiment.

FIG. 4 is a graph showing an example of the change of a powerperformance factor in a predetermined normal state and a predeterminedcharging priority state according to the embodiment.

FIG. 5 is a graph showing an example of a correspondence relationshipbetween an assist amount and an ascending gradient DE or an acceleratoropening AP that are set for each of a plurality of predeterminedascending gradients DE and predetermined accelerator openings AP in acruise state according to the embodiment.

FIG. 6 is a graph showing an example of a correspondence relationshipbetween the amount of generated power and an ascending gradient DE or anaccelerator opening AP in a cruise state according to the embodiment.

FIG. 7 is a graph showing an example of a correspondence relationshipbetween the amount of generated power and an engine speed NE in apredetermined normal state and a predetermined charging priority stateof a cruise state according to the embodiment.

FIG. 8 is a graph showing an example of a correspondence relationshipbetween an idle speed and a residual capacity SOC in a predeterminednormal state and a predetermined charging priority state of an idleoperating state according to the embodiment.

FIG. 9 is a graph showing an example of a correspondence relationshipbetween the amount of generated power and a residual capacity SOC in apredetermined normal state and a predetermined charging priority stateof an idle operating state according to the embodiment.

FIG. 10 is a flowchart illustrating a process for controlling an assistoperation of a motor in an acceleration state and a low accelerationstate according to the embodiment.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

-   -   11: internal combustion engine.    -   12: motor (generator motor).    -   15: high voltage battery (capacitor).    -   16: control device (driving force assisting unit, switching        unit, threshold value increasing unit, generated power        increasing unit, generated power changing unit, residual        capacity acquisition unit, idle speed setting unit,        determination unit, threshold residual capacity increasing unit,        idle stop prohibiting unit, and traveling road determining        unit).    -   24: gradient sensor (gradient acquisition unit).

BEST MODE FOR CARRYING OUT THE INVENTION

A control apparatus for a hybrid vehicle according to an embodiment ofthe invention will be described below with reference to accompanyingdrawings.

A hybrid vehicle 1 according to this embodiment is a parallel hybridvehicle where an internal combustion engine (ENG) 11, a motor (MOT) 12,and a transmission (T/M) 13 are directly connected to each other inseries as shown in FIG. 1. Driving forces of the internal combustionengine 11 and the motor 12 are distributed and transmitted to left andright driving wheels W and W through the transmission 13 and adifferential (not shown). When a driving force is transmitted from thedriving wheel W to the motor 12 during the deceleration of the hybridvehicle 1, the motor 12 functions as a generator so as to generate aso-called regenerative braking force, and recovers the kinetic energy ofthe vehicle body in the form of electrical energy. The motor 12 isdriven as a generator by the output of the internal combustion engine 11according to the operating state of the hybrid vehicle 1, and thusgenerates power generating energy.

The motor 12 is composed of, for example, a 3-phase (U-phase, V-phase,and W-phase) DC brushless motor, and is connected to a power drive unit(PDU) 14 that controls the drive and generation of the motor 12.

The power drive unit 14 includes a PWM inverter, which performspulse-width modulation (PWM) and includes a bridge circuit. The bridgecircuit is formed by the bridge-connection using a plurality ofswitching elements of transistors.

A high voltage battery 15, which supplies and receives power (forexample, the supply power to be supplied to the motor 12 during theassist operation or the drive of the motor 12, or the output poweroutput from the motor 12 when the motor 12 generates electric power by aregenerative operation or step-up drive) to and from the motor 12, isconnected to the power drive unit 14.

Further, the power drive unit 14 receives a control command from acontrol device 16 and controls the drive and generation of the motor 12.For example, the power drive unit converts DC power, which is outputfrom the high voltage battery 15, into three-phase AC power during thedrive of the motor 12 on the basis of a torque command output from thecontrol device 16, and then supplies the three-phase AC power to themotor 12. Meanwhile, when the motor 12 generates electric power, thepower drive unit converts the three-phase AC power output from the motor12 into DC power, and charges the high voltage battery 15.

The power converting operation of the power drive unit 14 is controlledaccording to a pulse that is input from the control device 16 to a gateof each of the transistors of the bridge circuit of the PWM inverter,that is, a pulse that turns on or off each of the transistors by thepulse-width modulation (PWM). A map (data) of a pulse duty ratio, thatis, an ON/OFF ratio is previously stored in the control device 16.

A 12V battery 18, which is composed of various kinds of auxiliarymachineries and drives an electrical load 17, is connected in parallelto the power drive unit 14 and the high voltage battery 15 through aDC-DC converter 19.

The DC-DC converter 19 of which a power converting operation iscontrolled by the control device 16 is, for example, a bidirectionalDC-DC converter. The DC-DC converter steps down a voltage betweenterminals of the high voltage battery 15 or a voltage between terminalsof the power drive unit 14 during the regenerative operation or step-updrive of the motor 12 to a predetermined voltage level, and charges the12V battery 18. Further, when the residual capacity (SOC: State OfCharge) of the high voltage battery 15 is decreased, the DC-DC convertercan step up the voltage between terminals of the 12V battery 18 and cancharge the high voltage battery 15.

The control device 16 controls the state of the vehicle corresponding tothe operating states of the internal combustion engine 11 and the motor12, the power converting operation of each of the power drive unit 14and the DC-DC converter 19, the operating state of the electrical load17, and the like.

For this reason, signals output from various sensors that detect thestate of a power plant (that is, the internal combustion engine 11 andthe motor 12), and a signal that is output from a shift switch 28indicating the state SH of the transmission 13 corresponding to adriver's input operation are input to the control device 16. Forexample, the various sensors include a rotational speed sensor 21 thatdetects the engine speed NE of the internal combustion engine 11, arotation angle sensor (not shown) that detects the position of amagnetic pole (phase angle) of a rotor of the motor 12, a wheel speedsensor 22 that detects the rotational speed (wheel speed) NW of a drivenwheel in order to detect the speed of a vehicle (vehicle speed), anaccelerator opening sensor 23 that detects an accelerator opening APcorresponding to the accelerator operation amount operated by a driver,a gradient sensor 24 that detects the gradient of a traveling road (forexample, the ascending gradient DE), a current sensor 25 that detectsthe charging current and the discharge current (battery current IB) ofthe high voltage battery 15, a voltage sensor 26 that detects thevoltage between the terminals of the high voltage battery 15 (batteryvoltage VB), and a temperature sensor 27 that detects the temperature ofthe high voltage battery 15 (battery temperature TB).

The gradient sensor 24 detects the gradient of a traveling road on thebasis of, for example, the detection result of an acceleration sensorthat detects the acceleration of a vehicle in a longitudinal directionof the vehicle when the vehicle is stopped, or on the basis of theresult of, for example, the comparison between the detection value of adriving force of the vehicle and a predetermined traveling resistance ofthe vehicle on a flat road.

The control device 16 detects the residual capacity SOC of the highvoltage battery 15 by, for example, a current integration method. In thecurrent integration method, the control device 16 calculates the amountof integrated charging current and the amount of integrated dischargecurrent by integrating the charging current and the discharge current ofthe high voltage battery 15, which are detected by the current sensor25, for each predetermined period. Further, the control devicecalculates the residual capacity SOC by adding or subtracting the amountof integrated charging current and the amount of integrated dischargecurrent to or from the residual capacity obtained in an initial state orimmediately before the beginning of charge and discharge. In this case,the control device 16 performs, for example, a predetermined process forcorrecting the internal resistance changed due to the batterytemperature TB, or a predetermined correcting process according to thestorage voltage VB of the high voltage battery 15.

The hybrid vehicle 1 according to this embodiment has theabove-mentioned structure. Next, the operation of the control device 16for the hybrid vehicle 1 will be described.

For example, when it is detected that the state SH of the transmission13 corresponding to the driver's input operation is changed from a Drange corresponding to a normal traveling mode to an L range where arelatively large engine brake is obtained due to the signal output from,for example, the shift switch 28, or it is detected that the travelingroad has a predetermined ascending gradient due to the signal outputfrom, for example, the gradient sensor 24, the control device 16switches the operating states of the internal combustion engine 11 andthe motor 12 from a predetermined normal state to a charging prioritystate where the charging of the high voltage battery 15 relatively haspriority.

For example, like a charging priority state shown in Table 1, thecontrol device 16 sets predetermined control states when the operatingstates of the internal combustion engine 11 and the motor 12 arecontrolled, according to a predetermined vehicle state that includes atraveling state and a stop state of the vehicle and a predeterminedresidual capacity SOC of the high voltage battery 15. Further, thepredetermined control contents according to the ascending gradient DE ofthe traveling road are set in each of the control states.

TABLE 1 Low ascending (accelerator medium ascending (accelerator highascending (accelerator Vehicle state SOC Control state opening: small)opening: medium) opening: large to maximum) Acceleration High AssistAssist amount decrease or zero Assist amount decrease or zero Assistamount increase (the same as normal state) Acceleration Medium AssistAssist amount decrease or zero Assist amount decrease or zero Assistamount increase (the same as normal state) Acceleration Low AccelerationGenerated power increase Generated power increase Generated powerdecrease or zero charging Low High Assist Assist amount decrease or zeroAssist amount decrease or zero Assist amount increase acceleration (thesame as normal state) Low Medium Assist Assist amount decrease or zeroAssist amount decrease or zero Assist amount increase acceleration (thesame as normal state) Low Low Acceleration Generated power increaseGenerated power increase Generated power decrease or zero accelerationcharging Cruise High Cruise charging Generated power decrease or zeroGenerated power decrease or zero Generated power decrease or zero (thesame as normal state) (the same as normal state) (the same as normalstate) Cruise Medium Cruise charging Generated power increase Generatedpower increase Generated power decrease or zero Cruise Low Cruisecharging Generated power increase Generated power increase Generatedpower decrease or zero Stop High Idle stop Performing Performingprohibition Performing prohibition (the same as normal state) (the sameas normal state) (the same as normal state) Stop Medium Idle stopPerforming Performing prohibition Performing prohibition (the same asnormal state) (the same as normal state) (the same as normal state) StopLow Idle charging Generated power increase Generated power increaseGenerated power increase NE increase Deceleration — RegenerationPredetermined regenerative amount Predetermined regenerative amountPredetermined regenerative amount (the same as normal state) (the sameas normal state) (the same as normal state)

For example, in Table 1, a predetermined vehicle state includes anacceleration state that is caused by a relatively high acceleration, alow acceleration state that is caused by a relatively low acceleration,a cruise state that is caused by substantially constant speed traveling,a stop state, and a deceleration state.

The predetermined residual capacity SOC is composed of a high statehaving a relatively high residual capacity SOC, a low state having arelatively low residual capacity SOC, and a medium state having aresidual capacity SOC between the capacities of the high and low states.

The predetermined control states are composed of an assist state thatassists the driving force of the internal combustion engine 11 by thedriving force of the motor 12, an acceleration charging state thatoperates the motor 12 as a generator in the acceleration state or thelow acceleration state by the driving force of the internal combustionengine 11, a cruise charging state that operates the motor 12 as agenerator in the cruise state by the driving force of the internalcombustion engine 11, an idle charging state that operates the motor 12as a generator in an idle operating state during the stop of the vehicleby the driving force of the internal combustion engine 11, and aregenerative state that performs the regenerative operation of the motor12 in the deceleration state.

First, if the charging priority state is selected as the operatingstates of the internal combustion engine 11 and the motor 12, thecontrol device 16 changes a predetermined determination threshold valuecorresponding to a driving force command (for example, the acceleratoropening AP) to the vehicle, that is, an assist performing determinationthreshold value used to determine whether an assist operation forassisting the driving force of the internal combustion engine 11 by thedriving force of the motor 12 needs to be performed, into a value higheras compared to the predetermined normal state.

For example, if the assist performing determination threshold value isswitched from a threshold value AP1 in the predetermined normal state toa threshold value AP2 (>AP1) in the charging priority state as shown inFIG. 2, a region where the performing of the assist operation isprohibited is increased with respect to an accelerator opening AP andthe torque of the vehicle, the relatively accelerator opening AP isrelatively small or moderate, for example, like in the high state andthe medium state of the residual capacity SOC in the acceleration stateand the low acceleration state shown Table 1. In a low ascending ormedium ascending state where the ascending gradient DE of the travelingroad is relatively small or moderate, the assist amount is set to zeroso that the performing of the assist operation is prohibited.

In addition, if the charging priority state is selected, the controldevice 16 increases the amount of generated power of the powergenerating operation of the motor 12, which is performed by the drivingforce of the internal combustion engine 11, as compared to thepredetermined normal state.

Further, even when the assist operation is allowed to be performed inthe charging priority state, the control device 16 decreases the assistamount to a value (for example, the L range shown in FIG. 3) lower ascompared to the predetermined normal state (for example, the D rangeshown in FIG. 3), for example, as shown in the high state and the mediumstate of the residual capacity SOC in the acceleration state and the lowacceleration state of FIG. 3 and Table 1. Further, when the controldevice reaches a predetermined high ascending state where the ascendinggradient DE of the traveling road is relatively large (for example, in astate where the accelerator opening AP is maximum), that is, in a statewhere the accelerator opening AP is relatively large, the assist amountis set to a value equal to the assist amount in the predetermined normalstate.

Meanwhile, for example, according to a correspondence relationshipbetween the assist amount and the ascending gradient DE or theaccelerator opening AP shown in FIG. 3, a relatively large assist amountis set in the predetermined normal state regardless of the change of theascending gradient DE or the accelerator opening AP, and the assistamount is set to be increased toward the assist amount in thepredetermined normal state with the increase of the ascending gradientDE or the accelerator opening AP in the charging priority state.

When the assist operation is allowed to be performed in the chargingpriority state, for example, the control device 16 suppresses theperforming of the assist operation that is performed by the motor 12 inorder to decrease fuel consumption of the internal combustion engine 11as shown in FIG. 4, facilitates to the performing of the assistoperation that is performed by the motor 12 in order to ensure desiredpower performance (for example, ascending performance or the like), andchanges the power performance factor representing the contents of theassist operation of the motor 12 from zero of the fuel efficiency assistto 1 of the power performance assist.

Meanwhile, for example, according to a correspondence relationshipbetween a power performance factor and the speed of a vehicle (vehiclespeed) shown in FIG. 4, the power performance factor is changed andincreased from zero of the fuel efficiency assist to 1 of the powerperformance assist in the predetermined normal state (for example, the Drange shown in FIG. 4) with the increase of the vehicle speed, and thepower performance factor is set to 1 of the power performance assist inthe charging priority state (for example, the L range of FIG. 4)regardless of the change of the vehicle speed.

Accordingly, while a desired driving force is ensured by preferentiallyusing the driving force of the internal combustion engine 11 on anascending road, it is possible to prevent the assist operation frombeing excessively performed by the motor 12 and to effectively use thedriving force of the motor 12.

For example, like in the low state of the residual capacity SOC in theacceleration state and the low acceleration state shown in Table 1, inthe low ascending or medium ascending state where the relativelyaccelerator opening AP is relatively small or moderate in the chargingpriority state and the ascending gradient DE of the traveling road isrelatively small or moderate, the control device 16 changes the assiststate and sets the acceleration charging state that operates the motor12 as a generator by the driving force of the internal combustion engine11, and changes the amount of power generated by the motor 12 to a valuehigher as compared to the predetermined normal state. Meanwhile, in thiscase, as the amount of power generated by the motor 12 is increased, theload of the internal combustion engine 11 is increased.

Even when the acceleration charging state is set in the chargingpriority state, the control device 16 decreases the amount of powergenerated by the motor 12 or sets the amount of power generated by themotor to zero as compared to the low ascending or medium ascending statein the state where the accelerator opening AP is relatively large andthe high ascending state where the ascending gradient DE of thetraveling road is relatively large.

That is, when the ascending gradient DE is a predetermined thresholdgradient or less (for example, in the low ascending or medium ascendingstate), the control device 16 sets the amount of power generated by themotor 12 so that the amount of generated power is increased with theincrease of the ascending gradient DE. When the ascending gradient DE islarger than a predetermined threshold gradient (for example, in the highascending state), the amount of generated power is set to be decreasedwith the increase of the ascending gradient DE.

Accordingly, even in the acceleration state and the low accelerationstate, it is possible to increase the residual capacity SOC by the powergeneration of the motor 12 and to ensure a desired driving force by themotor 12 while ensuring an appropriate driving force corresponding tothe accelerator opening AP or the ascending gradient DE of the travelingroad.

Meanwhile, when the assist operation of the acceleration state and thelow acceleration state is allowed to be performed in the chargingpriority state, for example, the control device 16 sets the assistamount with reference to the map of the assist amount that is changedaccording to the engine speed NE previously set for each of a pluralityof predetermined ascending gradients DE and predetermined acceleratoropenings AP as shown in FIG. 5.

For example, according to a correspondence relationship between theengine speed NE and the assist amount shown in FIG. 5, the assist amountis set to be decreased with the increase of the engine speed NE.Further, the assist amount is set to be increased with respect to anappropriate engine speed NE with the increase of the ascending gradientDE and the accelerator opening AP.

The control device 16 sets a cruise charging state, which operates themotor 12 as a generator by the driving force of the internal combustionengine 11, in the cruise state that is caused by substantially constantspeed traveling. Further, when a charging priority state is set as theoperating states of the internal combustion engine 11 and the motor 12in the cruise charging state, the control device increases the amount ofgenerated power to a value (for example, in the L range shown in FIG. 6)higher as compared to the predetermined normal state (for example, inthe D range shown in FIG. 6), for example, as shown in the low state andthe medium state of the residual capacity SOC in the cruise state ofFIG. 6 and Table 1. Furthermore, when the control device reaches apredetermined high ascending state where the ascending gradient DE ofthe traveling road is relatively large (for example, in a state wherethe accelerator opening AP is maximum), that is, in a state where theaccelerator opening AP is relatively large from a state where theascending gradient DE of the traveling road is relatively small, thatis, in a state where the accelerator opening AP is relatively small, theamount of generated power is set to a value equal to the amount ofgenerated power (for example, zero) in the predetermined normal state.

Meanwhile, for example, according to a correspondence relationshipbetween the amount of generated power and the ascending gradient DE orthe accelerator opening AP shown in FIG. 6, the amount of generatedpower is set to be decreased toward zero with the increase of theascending gradient DE or the accelerator opening AP.

Accordingly, in the medium state and the low state where the residualcapacity SOC is relatively not large, it is possible to increase theresidual capacity SOC by the power generation of the motor 12 and toensure a desired driving force of the motor 12 while ensuring a desireddriving force by the internal combustion engine 11 in the cruise state.

Meanwhile, even when the cruise charging state is set in the cruisestate, for example, like the cruise state shown in Table 1, the controldevice 16 makes the amount of generated power be equal to that of apredetermined normal state in the high state of the residual capacitySOC, and decreases the amount of generated power or sets the amount ofgenerated power to zero as compared to the low state and the mediumstate of the residual capacity SOC.

That is, when the ascending gradient DE is a predetermined thresholdgradient or less (for example, in the low ascending or medium ascendingstate) in the cruise state that is caused by substantially constantspeed traveling, the control device 16 sets the amount of powergenerated by the motor 12 so that the generated amount of power isincreased with the increase of the ascending gradient DE. When theascending gradient DE is larger than a predetermined threshold gradient(for example, in the high ascending state), the amount of generatedpower is set to be decreased with the increase of the ascending gradientDE.

When the cruise charging state of the cruise state is set, for example,as shown in FIG. 7, the control device 16 sets the amount of generatedpower with reference to the map of the amount of generated power changedaccording to the engine speed NE.

For example, according to a correspondence relationship between theengine speed NE and the amount of generated power shown in FIG. 7, theamount of generated power is set to be increased with the increase ofthe engine speed NE.

If the charging priority state is selected as the operating states ofthe internal combustion engine 11 and the motor 12 during the stop ofthe vehicle, the control device 16 changes a predetermined determinationthreshold value of the residual capacity SOC, that is, an idle chargingdetermination threshold value used to determine whether a powergenerating operation of the motor 12 in the idle operating state of theinternal combustion engine 11 during the stop of the vehicle needs to beperformed, into a value higher as compared to the predetermined normalstate.

Accordingly, in the charging priority state, a region where the powergenerating operation of the motor 12 in the idle operating state isperformed is increased with respect to the residual capacity SOC, andthe residual capacity SOC is increased.

In addition, the control device 16 prohibits the stop of the idleoperation of the internal combustion engine 11 in the charging prioritystate, and increases the amount of generated power of the powergenerating operation of the motor 12 that is performed by the drivingforce of the internal combustion engine 11 as compared to thepredetermined normal state.

In addition, if the residual capacity SOC becomes a predeterminedresidual capacity or less, the control device 16 increases the enginespeed NE (idle speed) in the idle operating state as compared to whenthe residual capacity SOC is larger than a predetermined residualcapacity, or sets an idle speed so that the idle speed is increased withthe decrease of the residual capacity SOC.

When the idle charging is allowed to be performed in the chargingpriority state, for example, as shown in FIGS. 8 and 9, the controldevice 16 increases the amount of power generated by the motor 12 andthe engine speed NE (idle speed) of the internal combustion engine 11 ofthe idle operating state to a value (for example, the L range shown inFIGS. 8 and 9) higher as compared to the predetermined normal state (forexample, the D range shown in FIGS. 8 and 9). Further, the controldevice 16 prohibits the stop of the idle operation of the internalcombustion engine 11.

According to a correspondence relationship between the idle speed andthe residual capacity SOC shown in FIG. 8, in a predetermined normalstate, the idle speed is set not to be changed in the high state and themedium state of the residual capacity SOC, and the idle speed is set tobe increased with the decrease of the residual capacity SOC in the lowstate of the residual capacity SOC. In contrast, in the chargingpriority state, the idle speed is set not to be changed in the highstate of the residual capacity SOC, and the idle speed is set to beincreased with the decrease of the residual capacity SOC in the mediumstate and the low state of the residual capacity SOC.

According to a correspondence relationship between the residual capacitySOC and the amount of generated power in the idle operating state shownin FIG. 9, in a predetermined normal state, the amount of generatedpower is set not to be changed in the high state and the medium state ofthe residual capacity SOC, and the amount of generated power is set tobe increased with the decrease of the residual capacity SOC in the lowstate of the residual capacity SOC. In contrast, in the chargingpriority state, the amount of generated power is set not to be changedin the high state of the residual capacity SOC, and the amount ofgenerated power is set to be increased with the decrease of the residualcapacity SOC in the medium state and the low state of the residualcapacity SOC.

When the idle charging is allowed to be performed in the chargingpriority state during the stop of the vehicle, the control device 16sets the amount of power generated by the motor 12 so that the amount ofgenerated power is increased with the increase of the ascendinggradient.

For example, as shown in the low ascending state where the ascendinggradient DE of the traveling road is relatively small, that is, a statewhere the accelerator opening AP in the stop state of Table 1 isrelatively small, even in the charging priority state, the controldevice 16 stops the idle operation in the high state and the mediumstate of the residual capacity SOC like in the predetermined normalstate. In contrast, unlike in the predetermined normal state, in the lowstate of the residual capacity SOC of the charging priority state, thecontrol device prohibits the stop of the idle operation and increase theamount of generated power of the idle operating state.

Even in the charging priority state of the stop state, for example, asshown in Table 1, in the high state and the medium state of the residualcapacity SOC like in the predetermined normal state, the control device16 stops the idle operation in the low ascending state where theascending gradient DE of the traveling road is relatively small, that isa state where the accelerator opening AP is relatively small. Thecontrol device prohibits the stop of the idle operation in the highstate and the medium state, that is, a state the ascending gradient DEof the traveling road is relatively small, that is, a state where theaccelerator opening AP is relatively medium or large, and increases theamount of the generated power in the idle operating state.

That is, when the ascending gradient DE is larger than a predeterminedthreshold gradient, the control device 16 prohibits the stop of the idleoperation and increases the amount of power generated by the motor 12using the driving force of the internal combustion engine 11 during theidle operation as compared to when the ascending gradient DE is apredetermined gradient or less.

A process for controlling the assist operation of the motor 12 in theacceleration state and the low acceleration state will be describedbelow.

First, for example, in Step S01 shown FIG. 10, the engine speed NEdetected by the rotational speed sensor 21 is acquired.

In Step S02, the accelerator opening AP detected by the acceleratoropening sensor 23 is acquired.

In Step S03, the ascending gradient DE of the traveling road detected bythe gradient sensor 24 is acquired.

In Step S04, the residual capacity SOC of the high voltage battery 15 isacquired.

In Step S05, it is determined whether the ascending gradient DE islarger than a predetermined first threshold value.

If this determination result is “NO”, the process proceeds to Step S10to be described below.

Meanwhile, if this determination result is “YES”, the process proceedsto Step S06.

Further, in Step S06, it is determined whether the state SH of thetransmission 13 is in the L range (charging priority range) on the basisof the output signal of the shift switch 28 that corresponds to thedriver's input operation.

If this determination result is “YES”, the process proceeds to Step S08to be described below.

Meanwhile, if this determination result is “NO”, the process proceeds toStep S07.

Further, in Step S07, the assist amount is acquired by the map search ofan assist MAP that sets the assist amount corresponding to the enginespeed NE and the accelerator opening AP in the predetermined normalstate, and a series of processes are terminated.

Furthermore, in Step S08, it is determined whether the residual capacitySOC of the high voltage battery 15 is larger than a predeterminedcalculated capacity.

If this determination result is “YES”, the process proceeds to theabove-mentioned Step S07.

Meanwhile, if this determination result is “NO”, the process proceeds toStep S09.

Further, in Step S09, the assist amount is acquired by the map search ofthe engine speed NE and the accelerator opening AP on a first assistMAP, which corresponds to the large gradient (or high gradient), forexample, shown in FIG. 5, and a series of processes are terminated.

In Step S10, it is determined whether the ascending gradient is largerthan a predetermined second threshold value smaller than the firstthreshold value.

If this determination result is “NO”, the process proceeds to Step S14to be described below.

Meanwhile, if this determination result is “YES”, the process proceedsto Step S11.

In Step S11, it is determined whether the state SH of the transmission13 is in the L range (charging priority range) on the basis of theoutput signal of the shift switch 28 that corresponds to the driver'sinput operation.

If this determination result is “NO”, the process proceeds to theabove-mentioned Step S07.

Meanwhile, if this determination result is “YES”, the process proceedsto Step S12.

In Step S12, it is determined whether the residual capacity SOC of highvoltage battery 15 is larger than a predetermined calculated capacity.

If this determination result is “YES”, the process proceeds to theabove-mentioned Step S07.

Meanwhile, if this determination result is “NO”, the process proceeds toStep S13.

Further, in Step S13, the assist amount is acquired by the map search ofthe engine speed NE and the accelerator opening AP on a second assistMAP, which corresponds to the medium gradient, for example, shown inFIG. 5, and a series of processes are terminated.

In Step S14, it is determined whether the state SH of the transmission13 is in the L range (charging priority range) on the basis of theoutput signal of the shift switch 28 that corresponds to the driver'sinput operation.

If this determination result is “NO”, the process proceeds to theabove-mentioned Step S07.

Meanwhile, if this determination result is “YES”, the process proceedsto Step S15.

In Step S15, it is determined whether the residual capacity SOC of thehigh voltage battery 15 is larger than a predetermined calculatedcapacity.

If this determination result is “YES”, the process proceeds to theabove-mentioned Step S07.

Meanwhile, if this determination result is “NO”, the process proceeds toStep S16.

In Step S16, the assist amount is acquired by the map search of theengine speed NE and the accelerator opening AP on a third assist MAP,which corresponds to the small gradient, for example, shown in FIG. 5,and a series of processes are terminated.

As described above, according to the control device 16 for the hybridvehicle 1 of the embodiment, when the charging priority state isselected, the assist performing determination threshold value used todetermine whether the driving force of the internal combustion engine 11is assisted by the driving force of the motor 12 is increased ascompared to when the predetermined normal state is selected.Accordingly, it is possible to suppress the drive of the motor 12, tosuppress the power consumption required for driving the motor 12, and toprevent the residual capacity SOC of the high voltage battery 15 frombeing excessively decreased. Further, for example, even if a vehicletravels on an ascending road for a long time, or even if the ascendinggradient of an ascending road corresponds to a relatively high gradient,it is possible to ensure a desired driving force of the motor 12 that isused to assist the driving force of the internal combustion engine 11.

Furthermore, when the charging priority state is selected, the amount ofgenerated power of the power generating operation of the motor 12 isincreased by the driving force of the internal combustion engine 11 ascompared to when the predetermined normal state is selected. Therefore,it is possible to increase the residual capacity SOC of the high voltagebattery 15 and to easily ensure a desired driving force of the motor 12that is used to assist the driving force of the internal combustionengine 11.

In addition, since the amount of power generated by the motor 12 isincreased during the stop of the vehicle or the constant speed travelingstate of the charging priority state, it is possible to increase theresidual capacity SOC of the high voltage battery 15 as compared to thepredetermined normal state. Further, since the stop of the idleoperation is prohibited during the stop of the vehicle and the idlespeed is increased if the residual capacity SOC becomes a predeterminedresidual capacity or less, it is possible to easily ensure the desiredresidual capacity by the power generation of the motor 12 that is causedby the driving force of the internal combustion engine 11.

Furthermore, in the charging priority state, the idle chargingdetermination threshold value of the residual capacity SOC used todetermine whether a power generating operation of the motor 12 in theidle operating state of the internal combustion engine 11 during thestop of the vehicle needs to be performed (that is, an upper limitthreshold value for allowing the power generating operation to beperformed) is increased as compared to a predetermined normal state.Accordingly, it is possible to increase a region, which allows the powergenerating operation to be performed, of the residual capacity SOC ofthe high voltage battery 15, and to easily increase the residualcapacity SOC.

Meanwhile, according to the above-mentioned embodiment, in the chargingpriority state, the control device 16 has changed the assist performingdetermination threshold value of the driving force command (for example,the accelerator opening AP) of the vehicle into a value higher ascompared to the predetermined normal state. The invention is not limitedthereto. For example, when the ascending gradient DE detected by thegradient sensor 24 is larger than a predetermined gradient, the assistperforming determination threshold value may be changed into a valuehigher as compared to when the ascending gradient DE is smaller than apredetermined gradient (for example, in the state of a flat road).

In addition, for example, in a state where a driving force command (forexample, the accelerator opening AP) is smaller than the assistperforming determination threshold value and the power generatingoperation of the motor 12 is performed by the driving force of theinternal combustion engine 11 when the ascending gradient DE is largerthan a predetermined gradient, the control device 16 set the amount ofpower generated by the motor 12 so that the amount of generated power isincreased with the increase of the ascending gradient DE if theascending gradient DE is a predetermined threshold gradient or less (forexample, in the low ascending or medium ascending state), and sets theamount of generated power so that the amount of generated power isdecreased with the increase of the ascending gradient DE if theascending gradient DE is larger than a threshold gradient (for example,in the high ascending state).

Further, as for the stop of the vehicle, when a vehicle is stopped onthe ascending road, the control device 16 increases the amount ofgenerated power of the power generating operation of the motor 12 by thedriving force of the internal combustion engine 11 of the idle operatingstate as compared to when the vehicle is stopped on the flat road,thereby increasing the engine speed NE (idle speed) of the internalcombustion engine 11.

According to this modification, it is possible to suppress the drive ofthe motor 12, to suppress the power consumption required for driving themotor 12, and to prevent the residual capacity SOC of the high voltagebattery 15 from being excessively decreased. Accordingly, for example,even if a vehicle travels on an ascending road for a long time, or evenif the ascending gradient of an ascending road corresponds to arelatively high gradient, it is possible to ensure a desired drivingforce of the motor 12 that is used to assist the driving force of theinternal combustion engine 11. Further, since the amount of generatedpower is changed according to the ascending gradient DE, it is possibleto ensure desired ascending performance while increasing the residualcapacity SOC of the high voltage battery 15.

Meanwhile, in the above-mentioned embodiment, the hybrid vehicle 1 hasbeen a parallel hybrid vehicle where the internal combustion engine(ENG) 11, the motor 12, and the transmission 13 has been directlyconnected to each other in series. However, the invention is not limitedthereto, and the hybrid vehicle may be a different type of hybridvehicle.

INDUSTRIAL APPLICABILITY

According to the invention, it is possible to provide a controlapparatus for a hybrid vehicle that can ensure desired ascendingperformance.

The invention claimed is:
 1. A control apparatus for a hybrid vehicleincluding an internal combustion engine and a generator motor that areused as power sources of a vehicle, a capacitor that supplies andreceives electrical energy to and from the generator motor, and adriving force assisting unit that assists a driving force of theinternal combustion engine by a driving force of the generator motorwhen a driving force command of the vehicle is larger than apredetermined determination threshold value, the control apparatuscomprising: a switching unit that selects an appropriate traveling rangeaccording to a state of transmission corresponding to a driver's inputoperation and a state of the internal combustion engine and of thegenerator motor from a plurality of traveling ranges including at leasta normal traveling range and a charging priority range forpreferentially charging the capacitor, and switches the ranges; and athreshold value increasing unit that increases, when the chargingpriority range is selected by the switching unit, the predetermineddetermination threshold value as compared to when the normal travelingrange is selected by the switching unit wherein the predetermineddetermination threshold value comprises an accelerator opening.
 2. Thecontrol apparatus for a hybrid vehicle according to claim 1, furthercomprising a generated power increasing unit that increases, when thecharging priority range is selected by the switching unit, an amount ofpower generated by the generator motor as compared to when the normaltraveling range is selected by the switching unit.
 3. The controlapparatus for a hybrid vehicle according to claim 1, further comprisinga generated power increasing unit that increases an amount of powergenerated by the generator motor when the traveling state of the vehicleis a constant speed traveling state and the charging priority range isselected by the switching unit.
 4. The control apparatus for a hybridvehicle according to claim 1, further comprising a generated powerincreasing unit that prohibits a stop of an idle operation of theinternal combustion engine during the stop of the vehicle when thecharging priority range is selected by the switching unit, and increasesan amount of power generated by the generator motor during the stop ofthe vehicle as compared to when the normal traveling range is selectedby the switching unit.
 5. The control apparatus for a hybrid vehicleaccording to claim 1, further comprising: a gradient acquisition unitthat acquires an ascending gradient of a traveling road for the vehicle;a traveling road determining unit for determining whether the travelingroad is an ascending road or a flat road, according to the ascendinggradient acquired by the gradient acquisition unit; and a generatedpower increasing unit that increases an amount of power generated by thegenerator motor while the idle operation of the internal combustionengine is performed during the stop of the vehicle when the vehicle isstopped on the ascending road as compared to when the vehicle is stoppedon the flat road.
 6. The control apparatus for a hybrid vehicleaccording to claim 1, further comprising: a gradient acquisition unitthat acquires an ascending gradient of a traveling road for the vehicle;a traveling road determining unit for determining whether the travelingroad is an ascending road or a flat road, according to the ascendinggradient acquired by the gradient acquisition unit; and a generatedpower increasing unit that increases idle speed and increases an amountof power generated by the generator motor while the idle operation ofthe internal combustion engine is performed during the stop of thevehicle when the vehicle is stopped on the ascending road as compared towhen the vehicle is stopped on the flat road.